African American DNA Research Forum

Is it smart to go to a company that has a large database of a 'variety' of populations? I know that I have a mixed ancestry and some DNA testing companies are weighted more toward one population as opposed to another. Example: the Cambridge Group. I have read the material from "Genelex" and wonder if you know anything about them. They suggest that MLE test be performed first. Then if more detail is requested, you go from there to typing Ancestry Informative Markers.
What tests and by whom have you preferred? I value your opinion.
Aurelia